1. Field of the Invention
The present invention relates to highly branched polyamidoamines, and to the preparation of highly branched polyamidoamines.
2. Description of Background and Other Information
Polyamidoamine-epichlorohydrin resins have been used extensively as wet strength agents for paper, and for other applications. These resins are typically prepared in a two step process.
In the first step, a polyamidoamine prepolymer is prepared from a diacid (e.g. adipic acid) and a polyamine (e.g., diethylenetriamine). Then in the second step, the prepolymer is reacted with epichlorohydrin in an amount equal to or greater than the amount of secondary amine groups in the prepolymer.
In the latter step, a small amount of the epichlorohydrin reacts to effect branching of the polymer, accompanied by an increase in molecular weight. However, the majority of the epichlorohydrin reacts with the prepolymer to give reactive functional groups--specifically, either aminochlorohydrin or azetidinium.
These wet strength resins can also be used as creping adhesives. Creping adhesives can also be prepared using lower levels of epichlorohydrin, resulting in lower levels of reactive functionality.